Do the rules for a Non-Immigrant 'ED' Visa in Thailand start counting from the entry date or the visa issue date?

When I arrived at the airport in Bangkok on December 14, 2017, I entered on a 30-day visa exemption stamp. On January 9th, I obtained a 30-day extension which allowed me to stay until February 11th. During the extension period, I received a Non-immigrant "ED" Visa which was valid from February 1st - May 1st (90 days). Since then, I have applied for and received an extension every 90 days. That is, until today. I went to the IO to apply for my final 90 day extension; however, they would only extend to December 14th. They told me that the one year on my visa starts when I first entered the country (even though I didn't get the visa until February 1st).

Can anyone confirm that this is correct? It seems to me that I should be able to stay here on that visa for one year from the date it was issued. Btw, all of my activity has been performed at the office in Korat. Thanks!